The opening day of women's soccer at the Olympics saw the heavily-favored United States stunned by Sweden while other medal contenders enjoyed successful openers. 

12 teams are split into three groups of four with the top two from each group advancing to the quarterfinals as well as two third-placed teams. All 12 countries entered in this year's field saw action.

Group E: Great Britain opens with victory over Chile, Japan rescues late point against Canada

Ellen White scored both goals for Great Britain as Team GB started their Olympics with a solid 2-0 win against a Chile side making their tournament debut.

White had already had a tap-in ruled out for offside when in the 18th minute, Lucy Bronze clipped to the far post where Lauren Hemp kept the ball alive and allowed the  to score her first Olympic goal.

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She doubled her tally when Bronze sent in another excellent cross and White acrobatically met it to finish past Chile goalkeeper Christiane Endler to seal all three points.

In the other Group E game, Christine Sinclair put Canada in front just six minutes into the match as she fired past Japan goalkeeper Ikeda Sakiko after the ball rebounded off of the post. The goal was her 187th in her 300th appearance for the 

A late charge from Japan saw Iwabuchi Mana of Arsenal beat Stephanie Labbe with a long-range strike in the 84th minute after fending off an attack by Canadian defenders Kadeisha Buchanan and Shelina Zadorsky.

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Group F: Netherlands trounce Zambia, Brazil shut out China

Vivianne Miedema scored four times as the Netherlands routed Zambia 10-3. The all-time leader in both the Women's Super League as well as Dutch history tallied in the ninth, 15th, 29th and 59th minutes.

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Lieke Martens found the back of the net twice for the 2019 World Cup finalists. This was the Netherlands' debut at the Olympics. Barbara Banda scored a hat-trick in defeat for the Copper Queens.

Marta scored twice as Brazil knocked off China 5-0. The 35-year old opened the scoring eight minutes into the match after being the quickest to react to a header by Debinha that hit the crossbar. 

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It was soon 2-0 when Debinha finished past Shimeng Peng after the Steel Roses goalkeeper had saved the initial shot by Beatriz. After China had a large spell of possession in the second half, the Selecao put the game to bed.

Marta grabbed her second on 74 minutes, Andressa Alves added a fourth and Beatriz rounded out the scoring. The game is also notable for Formiga becoming the oldest Olympic footballer ever at age 43. her seven Olympic appearances is also a record.

Group G: Sweden stun Team USA, Australia slip by New Zealand

Stina Blackstenius scored twice as the Swedes knocked off Team USA for a second consecutive Olympics after eliminating the Stars and Stripes in the 2016 quarterfinals. 

In the 25th minute, Sweden broke things open when forward Blackstenius headed home from a well-placed ball by Sofia Jakobsson. After Tobin Heath fired wide, Crystal Dunn made a goal-saving tackle in the 30th minute on Jakobsson as she drove towards the box.

Blackstenius made it 2-0 from a corner after the initial shot hit the post. At the other end, Christen Press hit the post from close range and substitute Lina Hurtig capped off the scoring with Blaguilt's third in the 72nd minute.

Australia also prevailed in Group G as they knocked off Oceania rivals New Zealand 2-1. Tameka Yallop put the Matildas in front after just 20 minutes. Samantha Kerr played a lovely back-heel to and she rifled one to the roof of the net.

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Less than ten minutes later, the lead was doubled. Kerr connected with a Steph Catley cross to finish past Football Ferns goalkeeper Erin Nayler, who got to it, but couldn't keep it out. Substitute Gabi Rennie pulled one back for New Zealand in stoppage time, but Australia hung on for the victory.